High performance understanding for stack traces (Make error logs more productive)
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Ben.Demystifier

NuGet version (Ben.Demystifier) Build status

High performance understanding for stack traces

.NET stack traces output the compiler transformed methods; rather than the source code methods, which make them slow to mentally parse and match back to the source code.

The current output was good for C# 1.0; but has become progressively worse since C# 2.0 (iterators, generics) as new features are added to the .NET languages and at C# 7.1 the stack traces are esoteric (see: Problems with current stack traces).

Make error logs more productive

Output the modern C# 7.0 features in stack traces in an understandable fashion that looks like the source code that generated them.

Demystified stacktrace

Usage

exception.Demystify()

Or instead of Environment.StackTrace

EnhancedStackTrace.Current()

Resolves the stack back to the C# source format of the calls (and is an inspectable list of stack frames)

Calling .ToString() on the Demystified exception will produce a string stacktrace similar to the following (without the comments):

System.InvalidOperationException: Collection was modified; enumeration operation may not execute.
   at bool System.Collections.Generic.List<T>+Enumerator.MoveNextRare()
   at IEnumerable<string> Program.Iterator(int startAt)+MoveNext()                       // Resolved enumerator
   at bool System.Linq.Enumerable+SelectEnumerableIterator<TSource, TResult>.MoveNext()  // Resolved enumerator
   at string string.Join(string separator, IEnumerable<string> values)                    
   at string Program+GenericClass<TSuperType>.GenericMethod<TSubType>(ref TSubType value) 
   at async Task<string> Program.MethodAsync(int value)                                  // Resolved async 
   at async Task<string> Program.MethodAsync<TValue>(TValue value)                       // Resolved async 
   at string Program.Method(string value)+()=>{} [0]                                     // lambda source + ordinal
   at string Program.Method(string value)+()=>{} [1]                                     // lambda source + ordinal 
   at string Program.RunLambda(Func<string> lambda)                                       
   at (string val, bool) Program.Method(string value)                                    // Tuple returning
   at ref string Program.RefMethod(in string value)+LocalFuncRefReturn()                 // ref return local func
   at int Program.RefMethod(in string value)+LocalFuncParam(string val)                  // local function
   at string Program.RefMethod(in string value)                                          // in param (readonly ref)    
   at (string val, bool) static Program()+(string s, bool b)=>{}                         // tuple return static lambda
   at void static Program()+(string s, bool b)=>{}                                       // void static lambda
   at void Program.Start((string val, bool) param)                                       // Resolved tuple param
   at void Program.Start((string val, bool) param)+LocalFunc1(long l)                    // void local function 
   at bool Program.Start((string val, bool) param)+LocalFunc2(bool b1, bool b2)          // bool return local function 
   at string Program.Start()                                                              
   at void Program()+()=>{}                                                              // ctor defined lambda  
   at void Program(Action action)+(object state)=>{}                                     // ctor defined lambda 
   at void Program.RunAction(Action<object> lambda, object state)                         
   at new Program(Action action)                                                         // constructor 
   at new Program()                                                                      // constructor 
   at void Program.Main(String[] args)                                                    

Calling .ToString() on the same exception would produce the following output

System.InvalidOperationException: Collection was modified; enumeration operation may not execute.
   at System.ThrowHelper.ThrowInvalidOperationException_InvalidOperation_EnumFailedVersion() // ? low value
   at System.Collections.Generic.List`1.Enumerator.MoveNextRare()                         
   at Program.<Iterator>d__3.MoveNext()                                                   // which enumerator?
   at System.Linq.Enumerable.SelectEnumerableIterator`2.MoveNext()                        // which enumerator?
   at System.String.Join(String separator, IEnumerable`1 values)                          
   at Program.GenericClass`1.GenericMethod[TSubType](TSubType& value)                     
   at Program.<MethodAsync>d__4.MoveNext()                                                // which async overload?
--- End of stack trace from previous location where exception was thrown ---              // ? no value
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()                      // ? no value
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) // ? no value
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()                           // ? no value
   at Program.<MethodAsync>d__5`1.MoveNext()                                              // which async overload?
--- End of stack trace from previous location where exception was thrown ---              // ? no value
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()                      // ? no value
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) // ? no value
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()                           // ? no value
   at Program.<>c__DisplayClass8_0.<Method>b__0()                                         //  ¯\_(ツ)_/¯
   at Program.<>c__DisplayClass8_0.<Method>b__1()                                         //  ¯\_(ツ)_/¯
   at Program.RunLambda(Func`1 lambda) 
   at Program.Method(String value)
   at Program.<RefMethod>g__LocalFuncRefReturn|10_1(<>c__DisplayClass10_0& )              // local function
   at Program.<RefMethod>g__LocalFuncParam|10_0(String val, <>c__DisplayClass10_0& )      // local function
   at Program.RefMethod(String value)
   at Program.<>c.<.cctor>b__18_1(String s, Boolean b)                                    //  ¯\_(ツ)_/¯
   at Program.<>c.<.cctor>b__18_0(String s, Boolean b)                                    //  ¯\_(ツ)_/¯
   at Program.Start(ValueTuple`2 param)                                                   // Tuple param?
   at Program.<Start>g__LocalFunc1|11_0(Int64 l)                                          // local function
   at Program.<Start>g__LocalFunc2|11_1(Boolean b1, Boolean b2)                           // local function
   at Program.Start()
   at Program.<>c.<.ctor>b__1_0()                                                         //  ¯\_(ツ)_/¯
   at Program.<>c__DisplayClass2_0.<.ctor>b__0(Object state)                              //  ¯\_(ツ)_/¯
   at Program.RunAction(Action`1 lambda, Object state)
   at Program..ctor(Action action)                                                        // constructor
   at Program..ctor()                                                                     // constructor
   at Program.Main(String[] args)

Which is far less helpful, and close to jibberish in places

Problems with current stack traces:

  • constructors

    Does not match code, output as .ctor and .cctor

  • parameters

    Do not specify qualifier ref, out or in

  • iterators

    Cannot determine overload <Iterator>d__3.MoveNext() rather than Iterator(int startAt)+MoveNext()

  • Linq

    Cannot determine overload

    Linq.Enumerable.SelectEnumerableIterator``2.MoveNext()

    rather than

    Linq.Enumerable+SelectEnumerableIterator<TSource, TResult>.MoveNext()

  • async

    Cannot determine overload and no modifier such as async

    <MethodAsync>d__5``1.MoveNext()

    rather than

    async Task<string> Program.MethodAsync(int value)

    Noise!

    --- End of stack trace from previous location where exception was thrown ---
    at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() 
    at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
    at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) 
    at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(Task task) 
    at System.Runtime.CompilerServices.TaskAwaiter.GetResult() 
    
  • lambdas

    Mostly jibberish <>c__DisplayClass2_0.<.ctor>b__0(Object state) with a suggestion of where they are declared but no hint if there are multiple overloads of the method.

  • local functions

    Mostly jibberish <RefMethod>g__LocalFuncParam|10_0(String val, <>c__DisplayClass10_0& ) with a suggestion of where they are declared but no hint if there are multiple overloads of the method.

  • generic parameters

    Not resolved, only an indication of the number RunLambda(Func``1 lambda) rather than RunLambda(Func<string> lambda)

  • value tuples

    Do not match code, output as ValueTuple``2 param rather than (string val, bool) param

  • primitive types

    Do not match code, output as Int64, Boolean, String rather than long, bool, string

  • return types

    Skipped entirely from method signature

Benchmarks

To run benchmarks from the repository root:

dotnet run -p .\test\Ben.Demystifier.Benchmarks\ -c Release -f netcoreapp2.0 All

Note: we're only kicking off via netcoreapp2.0, benchmarks will run for all configured platforms like net462.